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Fig. 14 Architecture of the neural network used in the recognition system
The weight update for the output neurons of the network can be determined as:
The error signal at the output of neuron j at iteration n is:
e j ð
n
Þ¼
d j ð
n
Þ
y j ð
n
Þ
ð
1
Þ
The instantaneous value of error for neuron j is 2 e j ð
n
Þ
.
Þ
of total error is obtained by summing 2 e j ð
Þ
The instantaneous value
n
n
of all
neurons in output layer
2 X
j 2 c
1
e j ð
Þ¼
Þ
ð
Þ
n
n
2
where,
includes all neurons in output layer.
Average squared error is given by
'
c
'
N X
N
n ¼ 1
1
e avg ¼
Þ
ð
Þ
n
3
e avg should be mini-
mized. Back-propagation is used to update the weights. Induced local
where, N is the total number of patterns in training set and
field v j ð
n
Þ
produced at input of activation function is given by
X
m
v j ð
n
Þ¼
w ji ð
n
Þ
y i ð
n
Þ
ð
4
Þ
i ¼ 0
where
'
m
'
is the number of inputs applied to neuron
'
j
'
, so the output can be written
as:
y j ð
n
Þ¼/ j ð
v j ð
n
ÞÞ
ð
5
Þ
.
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